Head suspensions for disk drives and other dynamic data storage devices are generally known and disclosed, for example, in the Tangren U.S. Pat. No. 5,850,319 and the Ruiz et al. U.S. Pat. No. 6,215,622.
An important performance-related criteria of a suspension is specified in terms of its resonance characteristics. For example, in order for the suspension to accurately position a read/write head slider with respect to a desired track on a magnetic disk, the suspension must be capable of precisely translating or transferring the motion of a positioning arm to the slider. An inherent property of moving mechanical systems, however, is their tendency to bend and twist in a number of different modes when driven back and forth at certain rates known as resonant frequencies. Any such bending or twisting of a suspension can cause the position of the head slider to deviate from its intended position with respect to the desired track. Since the head suspension assemblies must be driven at high rates of speed in high performance disk drives, it is desirable for the resonant frequencies of a suspension to be as high as possible. The detrimental effects of the bending and twisting at the resonance frequencies can also be reduced by minimizing the extent of the bending and twisting motion of the suspension (also known as the gain) at the resonant frequencies.
Common bending and twisting modes of suspensions are generally known and discussed, for example, in the Yumura et al. U.S. Pat. No. 5,339,208 and the Hatch et al. U.S. Pat. No. 5,471,734. Modes which result in lateral or transverse motion (also known as off-track motion) of the head slider are particularly detrimental since this motion causes the head slider to move from the desired track on the disk toward an adjacent track. The three primary modes which produce this transverse motion are known as the sway, first torsion and second torsion modes. The sway mode is a lateral bending mode (i.e., the suspension bends in the transverse direction along its entire length. The first and second torsion modes are twisting modes during which the suspension twists about a rotational axis which extends along the length of the suspension.
Various techniques for compensating for the detrimental effects of resonance modes are known and disclosed, for example, in the Yumura et al. and Hatch et al. U.S. patents mentioned above, as well as the Tangren U.S. Pat. No. 6,023,574. There remains, however, a continuing need for suspensions having improved resonance characteristics. Suspensions of this type that can be efficiently manufactured would be especially desirable.